


Step One: Plan A-head

by Illuminous_Anonymous



Category: Undertale (Video Game)
Genre: Accidental Voyeurism, Cloaca, Dubious Consent, Ectobiological Incest, Ectobiology, M/M, Mating Cycles/In Heat, Sexual Coercion, Sibling Incest, Xenophilia
Language: English
Status: Completed
Published: 2018-04-28
Updated: 2018-04-28
Packaged: 2019-04-28 22:35:46
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,308
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14459250
Author URL: https://archiveofourown.org/users/Illuminous_Anonymous/pseuds/Illuminous_Anonymous
Summary: In a way, it almost made sense to her. Papyrus never seemed to express sexual attraction to anyone according to Undyne, so she was surprised he even had a heat. Besides that, the only monster that he seemed to fawn over so much was his older brother. So this scenario, even though it felt like it was taken straight out of a porn manga, made some sense.





	Step One: Plan A-head

**Author's Note:**

> A chef meal from the [ old menu. ](http://illuminous-anonymous.tumblr.com/post/155244920058/step-1-plan-a-head)
> 
> Originally posted Jan. 1, 2017.

“Oh stars, come on Sans…”

Alphys dialed Sans’ number again, hoping that this time, the skeleton would pick up the phone. She hadn’t called him in a long time, but the situation was rather, uh, urgent, considering who was involved.

Papyrus had looked a little sick when he came to return Undyne’s anime disk for her–she was extra busy with work today, but had promised it’d get back to her, and what good skeleton friend wouldn’t help a bud keep their promise? He’d only looked a little sick. 

“Skeletons don’t get sick easily, Dr. Alphys! And certainly not I, the Great Papyrus!”

From his confidence, she’d kind of believed him. So when he wobbled and almost fell over while leaving, she’d almost been too shocked to help catch him. His bones were warm, some of his joints lightly flushed with the orange of his magic, and his sockets were half-lidded and a tad unfocused.

She felt her face flush at the realization. It wasn’t quite hard to notice the symptoms of heat.

Quickly, she’d ushered the skeleton into one of the rooms in the lab, telling him that she’d call his brother to come pick him up. He’d seemed to come to his senses a little more at that and accepted the notion, letting her leave him in the room.

Now, if his brother would just–

“heya.”

Alphys startled a bit, snapping out of her thoughts, “O-oh! Sans! Hello…”

“…uh, yeah. what’d you call for?”

“What?”

“what?”

“Oh! Right! Uh, hey, so, there’s something, ah, wrong with Pap–”

“Where is he?”

She kind of had a shock at the sudden change in his tone, but shook her head to snap out of it.

“Ah, uh, he’s in one of the rooms in my lab. He’d stopped by for Undyne, but apparently he didn’t know that he was–”

“which room?”

“YeEEK!” she turned swiftly to find Sans a little bit behind her in the lab. How did he do that? Why did he keep doing that?!

“G-geez Sans! You’ll give me a h-heart attack!” she wiped a little sweat off of her brow, “H-he’s in the room a little down the hall, the door to your left.”

“right, thanks.”

He moved pretty quickly for a usually lazy skeleton, but it seemed like Sans was always like that when his brother was involved. It was kind of endearing.

Suddenly realizing that she should probably tell the older skeleton what he was in for, she pulled up the camera for the room Papyrus was in on her screen to check his condition, and…

Papyrus was sitting on the cot in the corner of the room, his face obscured by his laced fingers and his downward gaze, his right foot constantly tapping against the ground. He looked caged in the room, something she hadn’t been trying to do. She hoped he didn’t feel too horrible…rather, she hoped he wasn’t too far along in his heat.

What did Papyrus do to deal with it anyway? From what Undyne told her, he never really expressed sexual attraction to anyone, and the only monster he really seemed to fawn over every once in a while was his brother. How did the tall skeleton deal with something like this for the whole heat week? Her thoughts cut short when she noticed the door starting to open.

When Sans entered the room, the tapping stopped abruptly, and his entire body seemed to shudder.

She blinked at the reaction, unsure of what that meant. The older skeleton had his hands up placatingly, mumbling something to him if his mouth movements were of any indication. She didn’t have the audio on, so she couldn’t hear what Sans was saying to the other skeleton, but whatever he said had the other nodding and calming down. Sans went over and tried to help his brother up–he was a tad too short to actually support him in any way, but he could help him stand at least.

Papyrus, however, didn’t try to get up. 

In a flash of movement, he grasped the small of his brother’s back and the side of his head, pulling him forward. Sans’ sockets widened, and she watched as he suddenly found himself kissing his brother, their teeth pressed close as miniscule, almost unseen sparks of magic flickered between them.

Oh.

Alphys felt her face go red, turning away from the screen.

No way. She had _not_ expected this.

For a good minute, her heart nearly beat out of her chest with excitement and anxiety at the same time. Two brothers kissing?! Gosh, it was just like one of her anime! Of course, Sans would probably be really embarrassed to be outed alongside his brother like this. How would he react to her knowing about their relationship? Would Sans give her an even wider berth now? How would…

Or maybe Papyrus was too far along in his heat to care, and Sans was just caught in the fray just now, and she was being stupid, too busy thinking of anime and kissing to stop something that Papyrus would regret.

Her body instantly cooled with a shudder, and she turned back to the screen, ready to do…to do…s-something!

Sans seemed to be in some distress, his hands scrabbling to get a hold of Papyrus’ grasping ones. He was giving some mixed signals though, since he was pushing into the kiss. Heck, when Papyrus summoned a long tongue and licked against Sans teeth, he reciprocated with his own, flatter one.

(Skeleton monsters could also use some ghost magic? That was definitely info for later…)

Still, she wouldn’t really be able to tell unless she could hear them. She’d had the audio for that room on mute, just in case Papyrus had decided to take care of things by himself. 

She felt herself freeze, though. She had a lot of cameras around the Underground in general, but this felt…invasive. Who knew what they were saying? It was already pretty intimate-looking. And…ugh, whatever! She needed to help Sans if things were going out of control in there!

Almost cautiously, she pressed the button to get the audio in the room and turned it up so she could hear what they were saying. With the volume up, she could hear the wetness of their kisses, and felt herself flush. She watched as Sans pulled his face away from Papyrus’. The younger skeleton appeared to be having none of that, pressing his tongue against Sans’ closed teeth.

“oh, sh-shit, Pap, w-hait…”

It was strange, seeing the usually cool and composed skeleton losing control, trying to keep Papyrus’ gloved hands from under his shirt. He gasped and squirmed when one hand squeezed high at his thighbone.

“Sans, please! I-I need…I need…” Papyrus cried and muttered against his brother’s teeth. The skeleton was almost shaking. God, he was so desperate.

“bro, you’ve gotta–ngh…you’ve gotta wait, we aren’t at home yet…”

“I need…I need you…I need you, brother, I need you…Please, brother…I-I need you…L-let me…let me…”

Sans seemed about as stunned as she felt, if not more, but it was Alphys who buried her face into her hands and resisted the urge to scream. Holy shit, that was…that was too much. Like, wow. Just the desperation in his voice made her soul shiver. She couldn’t imagine what Sans was feeling.

She could just barely hear Papyrus practically chanting something–it involved Sans’ name and more pleading–right by Sans’ head, and whatever he was saying made the other’s face turn blue. Sans jolted again, though, when a hand reached into the front of his shorts and did… _something_. Whatever that something was, it had Sans holding onto his arm while he did it, whispering something back to his brother even as he trembled in his grasp.

She knew she shouldn’t…this was supposed to be private. This was…

She turned up the volume, and while the quality decreased a little, she could make out more of what they were saying.

Almost as if to call her out on her absolute invasion of privacy, Sans started looking around, checking the walls for something. He was most likely looking for a camera. Smart decision, too, considering he knew about the hidden cameras she had all over the Underground.

He wouldn’t be finding the one she hid in there, though. That one was hidden in the clock.

The one he looked right at and quickly inspected before he looked for another potential place.

She felt her eyes narrow in disgust at herself.

“Saaaaaans…Saaaaaans please…I’m burning, I need… _Please…_ ” he tugged on whatever he had a grip on.

“Hck-okay, okay…just…just let me move a bit, Pap…”

“Will you…will you take care of me?” Papyrus moaned against the side of Sans’ head.

“hah…y-yeah. i’ll always help, Pap. i’m your big bro, remember? i’ll always take care of you…you’ve gotta let go, though–awh, Pap, don–hah–just…just for a little bit, okay? i can’t move with you holdin’ my symphysis…”

Alphys was no biologist, but she knew where Sans meant, and she placed both hands over her face. Stars, they were going to be the death of her–her heart was beating way too quickly while watching them. Not that she wanted to. She was just…making sure nothing bad happened. If Sans needed help, she’d call some in. That’s why she was watching.

That’s why she didn’t feel gross for doing so at all. Yep, no gross feelings there.

“after i do this, i need you to hold on till we get home. can you do that for me?” Sans looked up at his little brother, then reached up to hold his chin, “Pap?”

It took Papyrus a moment to respond, but he did, kissing his older brother as he slipped his hand out of Sans’ shorts, much to the other’s relief.

“i’m right here, bro, okay? i’m just…we can’t do it all here, but i can…just…just keep sittin’.”

Sans was bending down to kneel in between Papyrus’ legs, moving to adjust the younger skeleton’s bottoms.

Oh shit. _Oh shit._

Was he actually going to…

Her jaw dropped open a little as she covered her mouth, sweat breaking out along her brow as Sans kissed each of Papyrus’ vertebrae below the ribs, whispering praises to the other, until he reached his pelvis, where he leaned back and pulled the front of his shorts down.

Alphys actually clenched the front of her robe to keep her heart from hopping straight out of her chest. Instead of a dick or a pussy, both of which she’s seen many of and could mildly imagine being attached to Papyrus’ body, there was a long tentacle, one that dripped and wriggled lightly, glowing orange with magic as it searched for stimuli.

Her jaw snapped shut when Sans greeted the tentacle with what she assumed was a kiss to its slightly tapered head. It pressed against his teeth and Papyrus groaned with need, shifting his hips to get it closer to his brother. Sans seemed to pause for a moment before taking a hold of the base of the tentacle, beginning to jack it off, like how one would for a dick.

Alphys knew she shouldn’t be feeling any sort of way about how it looked–Sans in between his towering brother’s legs, apparently taking care of him as a good older brother should. She couldn’t help but wonder exactly how long Sans has been a “good older brother”. She had so many questions, one’s she’d rather die than ask, one’s Sans would probably rather die than answer.

When she got her focus back, she found that he’d graduated from jacking his brother off to licking at the base of the tentacle, which curled and quivered against the side of his face. She’d never had such a good look at Sans’ fangs before…they were pretty big. She’d never seen his tongue before either, nor had she ever seen Papyrus’ tongue, which licked against his teeth in an almost “licking your lips” sort of gesture. Without the lips, it just looked like he was hungry. 

He’d probably still look hungry with them.

She couldn’t hear whether Sans was moaning or not, the volume’s quality not able to catch much more. Besides, she wasn’t trying to out herself by booming the audio in the…shit.

Realizing her stupidity, she quickly moved away from the screen and ran upstairs, trying to find the right drawer. She shuffled through her things until she found her earphones–why hadn’t she thought of using them?! What if Papyrus made a noise that was too loud, and Sans heard it in the room twice? There was no telling exactly what Sans noticed most of the time! Shoot!

She almost tripped herself coming back down the stairs before she found the audio jack and plugged the earphones in. She sighed in relief, having dodged a bullet. Then she looked back up to the screen and felt her face nearly explode.

Sans had graduated from simply licking around the base of Papyrus’ tentacle to taking most of it into his mouth, and she could just barely see the blue of his tongue as he cradled the bottom of the dick in his mouth with it. His head bobbed slowly, Papyrus holding his skull with one hand and covering his mouth with the other.

For a moment, she stood there, watching, stupefied. Then she wondered why she couldn’t hear anything, and for a moment of horror, she thought that the camera or her computer were on the fritz. When she looked down at her hand and saw the earphones, she blushed at herself, placing the buds in her earholes.

“mmh, hhh, hhm, mhh…”

“Sans…Sans…oh, stARS…Brother…”

Papyrus leaned back onto the bed and arched, his hand pulling Sans toward his crotch even more, and Sans complied, shifting forward a little. Papyrus started to thrust a little, and though she couldn’t really see Sans’ expression from the angle of the camera, she could tell from the sounds that he was…adjusting.

“hhgk, hhhm, mhhh, hhmm…mmmm, mmmn, mmm…”

“Oh Brother, _please_ …ahh…hahhh…let…” Papyrus leaned up a little, trying to see Sans’ face, “let…let me…sex…please, brother… _please…_ ”

Sans paused, just as Alphys felt a little something run down her nose. She grabbed her chair and sat down, her eyes glued to the screen even as she dabbed her nose with a napkin.

Sans seemed to wait a moment before he sat up, letting the tentacle fall from his mouth. Before Papyrus could complain, he tugged on Papyrus’ battle body, directing him to get up before he backed away from the bed, still on his knees. A light seemed to go off in Papyrus’ head, and he started practically scrambling to stand. 

“heh, eager much?” Sans teased, opening his mouth to accommodate the other.

Had Papyrus been more coherent, he probably would’ve said words to reply. Instead, he just thrust most of his dick into his brother’s mouth, who gagged for a moment before he became more composed. From the loopy grin on Papyrus’ face, Alphys guessed Sans didn’t look to pleased, but allowed it anyway.

Sans adjusted around Papyrus as he held the back of his skull. After a moment, Papyrus began to thrust, bringing his hips and Sans’ head forward at the same time.

Sans made lightly choking noises around the other’s appendage, but he wasn’t scrambling about or making any desperate movements. So…apparently, he was enough in his element for the treatment he was getting. And gosh, it was some sort of treatment. He seemed to barely be able to get a breath in edgewise as Papyrus became more and more eager, the tall skeleton’s stamina definitely kicking in.

“Ohh, ahh, hhahh, yesssss…yes, ahh, mmah!”

Papyrus leaned his head back before looking down at his brother. He smiled lopsidedly at whatever he saw, and he gave a particularly hard thrust.

“You…you love this…like me, don’t you? I want more, too…”

He got back to it, and all the while, Alphys couldn’t see Sans’ face.

She really wanted to see it. It was wrong and gross and disgusting on her part, but for fucks sake, she wanted to see Sans’ face. What on earth did his face look like for even heat-delirious Papyrus to know what it meant? She should’ve put more than one camera in there. She’d been madder at herself for much more and less before, but gosh, how could she have been so stupid to have only one camera in there?

She shook her head, trying to get rid of the self-deprecating thoughts, just as Papyrus’ cries started to increase in pitch. She gazed up and noticed that Sans had taken a hold of Papyrus’ hips, the very ones that had increased in speed since she last focused. She could very barely hear Sans choking, but again, he wasn’t scrambling. He had to be fine.

Papyrus surely though he was, all the way to the end. With a full-body tremble, he groaned loudly and released straight into his brother’s mouth. His hips gave a few baby thrusts before he seemed completely spent, backing away until his knees hit the bed and he sat with a tired plop.

Sans coughed a bit, and she saw droplets of orange dotting the floor before he leaned his head back. With it back as it was, she could very barely see the slight tear marks on his face, and definitely noticed the flush across his cheekbones. His teeth were closed shut for a moment, then he swallowed, opening his mouth to breathe again.

Sans wiped his wrist near his mouth, gasping, “thhat…that should…be enough…c’mon, we need…to get–”

“Brother…I want…sex with you…”

“…Pap, you just got some, bro.”

Papyrus frowned, “No…no, not….no…”

Sans sighed, “please bro, you’ve gotta wait till we get-”

“I can’t wait! I’m…I’m burning!” Papyrus’ breath hitched, and Alphys felt her heart sink, “I’m burning and I need…I…I need…”

When she looked down, sure enough, his appendage hadn’t stayed flaccid for very long, the tentacle stiff and thick, wet and dripping all over again. Sans looked down at it, too, and, after another look around the room, seemed to give a resigned sigh.

“…scoot back on the bed, Paps.”

When his brother gave him a confused look, Sans gestured for him to scoot back on the bed away from him. Papyrus still didn’t seem to comprehend what Sans said completely, but he had at least started to scoot away

Sans, on the other hand, leaned his head forward, and after a moment, he reached into the front of his pants and started to…what Alphys assumed was fingering himself. It seemed that way, from how Papyrus’ focus snapped onto his brother and didn’t fade away–in fact, he’d stopped moving entirely, it was almost a little eerie to look at.

The smaller skeleton had started to arch his back outward just a bit, like he was trying to move away from his pleasure, and his shoulders shook a little. Papyrus shifted just the slightest, but Sans looked up at him. Something in Sans’ eyes told Papyrus to stay, because the younger skeleton didn’t move toward him again.

Sans huffed lowly one last time before he pulled his hand out of his pants, his fingers strangely blue and wet. He wiped his hand somewhere on the inside of the bottom of his pants before he climbed onto the cot, Papyrus watching him like a hawk all the while.

The short skeleton leaned onto his back, telling his brother to wait once more as he arched his back up to pull off his shorts. The more he pulled them down, the more blue ectoflesh he exposed, his chubby stomach shifting a little as he maneuvered himself around. Finally, he pulled them all the way past his ankles as he let his slippers flop off of his socked feet, and he dropped them down onto the floor.

Alphys choked on her own spit, watching as Sans laid back and opened his legs, his own, shorter but fatter tentacle laying wetly against his stomach, only shifting a little bit. Below the tentacle was a small, puckered hole, but just like their dicks, it was different as well, if the bubbled wet trail that came from it was any indication. 

She hadn’t seen Sans use any lube.

“be quick, bro…we need to get you hom-mmh!”

Papyrus was on him like a wild dog, grasping his hips to pull him in. He arched his body over Sans’, lining himself up with the other’s hole as he angled Sans’ body just right. Sans was saying something, but neither Papyrus or Alphys really listened.

One moment, the head of Papyrus’ dick was against the pucker of Sans’ lightly dripping hole. The next, he was more than halfway in, Sans’ ring of magic stretching.

Sans arched his back at the sudden intrusion, a choking sound escaping his open jaws as his hands clenched the sheet under him. His body trembled something fierce…perhaps Papyrus had hurt him. It looked like Papyrus noticed, at least dimly, that Sans appeared to be in some sort of pain, because a low whine left him and he pressed the rest of himself inside of his brother more slowly.

Alphys bit her nails as she watched Sans breath deeply, calming himself enough to stop trembling. He reached a hand up to caress his brother’s face, whispering something to him that made Papyrus feel more at ease. 

The romantics of it all made her tingle.

She wanted to throw up.

After a moment of letting Sans adjust, Papyrus held his hips as he started to pull out slowly. Sans brought himself up onto his elbows, sighing and twitching when Papyrus thrust back inside of him slowly.

“hhh…hahh…r-remember, Pap…just a quick one…just…ahhn…”

“Sans…Sans…yes…thank you…thank–hah…a-hhah…”

Sans was being thanked…thanked for permission to have sex with him.

Alphys’ mouth felt so dry, thirsting for those words to be said to her, preferably by Undyne.

Regardless of her fantasies, Papyrus kept up his slow pace for a little while before he started to periodically speed up. He kept a good hold on Sans’ hips as he did so, leaving his brother’s legs to do whatever they wished, which was usually to lay relatively limp.

Sans couldn’t keep his head up the whole time and laid back down for a little while every once in a while to just stare up and moan at his younger brother as he was used.

“c-c’mon…c’mon and finish, bro…let’s go home, k?”

Papyrus didn’t respond this time, just huffing and groaning with exertion. He leaned down to press kisses against Sans’ clavicles and neckbones. Sans groaned and probably clenched a bit, if Papyrus’ choked moan were any indication of it. 

Alphys didn’t notice that she was breathing really harsely until she paid attention to her mouth from watching Sans’ drop open. She tried shutting it, but she knew it’d just drop open again anyway.

As Papyrus increased his pace, he became more and more affectionate with Sans, kissing him wherever he could reach mid-thrust, and rubbing his forehead against his brother’s. Sans’ breathy grin became more genuine for a moment before he shook his head. He kissed Papyrus on the teeth again, then Papyrus moaned loudly into the air.

“yeah…hah…th-that’s it…c’mon and cum…y-you want to go home, don’cha?”

The taller skeleton groaned loudly again, his face against Sans’ neck. Then, he angled his hips a bit differently, pulling Sans’ body with him as he got himself into a better position to use his brother.

Almost instantly, the thrusts were different.

They were angled a bit more upward, and made Sans talk less. He was reduced to sighs and moans, occasionally letting out a louder one without meaning to. Sans started to cling to the bed sheets, too, his ribs clearly moving though he didn’t really need to breathe. Papyrus, though, didn’t seem completely satisfied. He kept adjusting the ways he thrusted, thought it generally remained fast, and growing faster.

Alphys watched, almost as if in a trance, as Sans’ hole accommodated his brother again and again. His own tentacle curled and squirmed in long movements against his stomach, experiencing pleasure even with no one touching it. 

She gazed at Sans’ expression, as he slowly lost more of his composure. He slowly spoke less and angled himself more, hurried his brother less and arched his back more. Even though Sans wasn’t in heat, it was like he was falling into it just like his brother was. The loss of control…the loss of time, thoughs, and sense felt…like a really nice idea.

Then, suddenly, Papyrus apparently found what he was looking for.

Sans’ half-mast sockets snapped open before they closed as his head fell back onto the bed. He keened into the open air of the room.

Alphys could see the corner of Papyrus’ happy grin before he thrust there quickly again. This time, Sans’ seemed to start trying to curl in on himself, his legs twitching and bending as he involuntarily mewled.

Just then, Sans noticed what he was doing and his socket snapped open again hastily, looking up at his brother in a panic.

“d-don’t aim there, Pap…not–!”

Papyrus stopped completely, looking up at his brother. This time, Alphys couldn’t see his look from where the camera was, but she did see Sans’ pupils grow. Papyrus leaned forward, near his brother’s head.

“I need…ah…your pleasure…I need you, Sans…”

“a-and, you have me, bro. you have me, and you…you can…you can m-mess me up all you want when we’re home, but–”

“Always, Brother…I want…need…I need you…to feel good.”

“i do! i do, bro, jus–aH!”

Sans ended up on his back again, Papyrus’ harsh thrust hitting wherever his big brother’s button was. It was clear Sans enjoyed it, too, a little bit of drool starting to trail from his jaw already.

“ahmMM~ n-no! don’t! not there! no! ah! nooo!”

Regardless of his growing, begging moans, Papyrus apparently kept going “there”, since Sans started arching his back again, like he was unsure of whether he wanted Papyrus to keep hitting his spot or to stop hitting it.

Sans writhed and moaned, holding onto sheets then onto clothes and arms, then onto sheets again. His pupils had grown pretty big, becoming hazy around the edges as he started looking upward. All the while, Papyrus stayed vigilant in his thrusts, even and he leaned forward to lick at Sans’ mouth trying to get the other’s tongue involved. 

His brother, of course, obliged, sticking his tongue out in a daze. Papyrus moved forward, pressing their teeth together with a small clack as his tongue went into Sans’ jaws. One of Sans’ hands reached up and grasped his shoulder because of this, but he just held him–Papyrus wasn’t pushed or pulled. Just held.

Alphys couldn’t help but watch. She couldn’t help but to listen. She’d been entranced by them. Bewitched even.

Her body, too, craved attention. Seeing the way Sans was being treated…she wanted that, too.

She wanted to be kissed, and held, and loved on. She wanted all of those things, even if she tried to push it away. Seeing Sans being pulled around like a ragdoll, being used for his brother’s pleasure while, even in his delirious state of heat, Papyrus sought to bring him pleasure as well…that…

With another one of Sans’ cries, she finally felt her hand touch the top of her pants before, trembling, she allowed her fingers to dip under the band.

Stars, she was the worst.

* * *

  


Papyrus and Sans didn’t finish for another 10 minutes.

Well, Sans finished earlier than that, but at that point, he couldn’t very well get Papyrus to stop. She was pretty sure Papyrus had wringed another orgasm out of the older skeleton in the midst of his own.

After they’d finished, Papyrus didn’t even bother pulling out before he nuzzled his head into Sans’ clavicles and conked out, still uncomfortably arched over his older brother. Sans barely moved, except to hug his brother’s shoulders after a minute or two.

It was sweet to watch.

She was trash for watching.

She couldn’t even give them relief while they rested.

She was sure she was fooling herself into thinking that she was just looking to monitor Sans’ and Papyrus’ vitals in case something happened while they were asleep.

Still, it gave her some purpose at the moment, so she heated up some ramen and played a puzzle game on a smaller screen while she watched them rest.

Fifteen more minutes passed before Sans trembled as he finally started to move again, attempting to slip out from under his younger brother, Alphys’ attention shifting from the game to him. She could see the look on his face this time, and gosh, she knew Sans didn’t seem to emote much, but that grin was one of regret and resignation if she’d ever seen it. 

Sans patted Papyrus’ shoulder, “c’mon pap…we’ve gotta get home…”

Papyrus didn’t complain this time, apparently sated enough in his heat to not be demanding. She watched as the taller skeleton slid out of his brother, Sans huffing once he was completely out, like he’d been holding his breath. At his low groan, she snapped out of the daze she was in.

Quickly, she changed the screen to look out at a random location in Waterfall, nearly pulling a muscle from how quickly she tried to move. She tried as hard as she could to get rid of the flush that had suddenly grown across her cheeks at the memory of what she’d seen the brothers do, but she knew it wouldn’t work. She had watched way too long, and she knew way too much.

After a moment, she heard the door open in the hallway and their slightly uncoordinated footsteps.

Breathing deeply, she gave up trying to look completely normal and turned to look at the brothers instead.

Papyrus was still dazed, but seemed a lot tamer than before. Sans, bless his soul, looked almost like he was normal, save for the limp to his gait and the dying flush of blue across his cheekbones. He had an indescribable look on his face, like a mix between irritation, resignation, questioning, and haste.

“look, uh, thanks for watching him till i got here,” he looked off to the side, his grin strained, “you’ll need to change the sheet. y’know how it is durin’ a heat. magic residue and whatnot.”

She didn’t have to touch her face to know it was red hot, “Uh, yeah, mm hmm, of course.”

The questioning part of his expression grew a little, but then he resigned his questions and sighed, pulling his brother along by his arm, “thanks again, Alph.”

“N-no problem.”

The skeletons hobbled over to the door as Sans muttered to his brother, something about staying still during the ride home. She heard it open and finally had the courage to look at their retreating backs, her eyes trailing over their features.

She ended up distracted when, for some reason, Sans paused, shuddered a little, then continued after his dazed brother.

When she looked for the reason why, she nearly choked on her own breath and had to turn away.

There was a small trail of orange starting to run down his leg.


End file.
